Modern wind turbines apply variable-pitch control, i.e. the rotor blades may rotate around a rotor blade centre axis. Therefore, the rotor blades are supported to a rotor hub by means of respective blade pitch bearings. Rotation of the rotor blades, that is the change of the respective pitch angle of the rotor blades is controlled by a rotor blade pitch control device adapted to control pitching of the respective rotor blades, i.e. the rotor blade pitch device adjusts the pitch angle of the respective rotor blades. Pitching of the rotor blades essentially depends on current climatic conditions such as the current wind speed and depends on control signals or control parameters such as the rotor speed reference and the power or torque reference. It is understood, that proper lubrication of the bearings is essential for maintaining the lifetime of the bearings and requires certain pitching of the rotor blades, making it important to the operation of the wind turbine as a whole.